The core implements a simple over-SPI protocol to convert SPI transactions into AHB Read or Write instructions. This over-SPI protocol supports only 32-bit-wide data accesses, which are translated to AHB-Lite accesses on the AHB-Lite master port. The bridge also monitors the AHB-Lite bus and reports erroneous transfers to the system. Errors captured by the core include Error Responses on the AHB bus, and errors due to slow responses for the accessed AHB-Lite slave.

The core supports quad, dual and single SPI data lines. The format of the lower level SPI transmission is compliant to the SPI de facto standard, but fixed to minimize area and power. The core drives the outbound serial data on the rising edge of the serial clock, and samples inbound serial data on the negative edge of the serial clock (CPHA=1), while the resting state of the serial clock is low (CPOL=0). Furthermore, all SPI transactions are assumed to be 32-bit wide.

The SPI2AHB core is designed with industry best practices, and its reliability and low risk have been proven through both rigorous verification and customer production. It is available in Verilog RTL source or as a targeted FPGA netlist, and its deliverables include sample synthesis and simulation scripts and comprehensive user documentation.

Block Diagram

Applications

The SPI2AHB enables an external device to have full access to the internal AHB-Lite bus over a simple SPI connection. It can be used for firmware uploads, design-initialization, and run-time monitor, control and debug in a wide variety of designs including typical microcontrollers, sensors, MEMs, and analogue front-ends.

Support

The core as delivered is warranted against defects for ninety days from purchase. Thirty days of phone and email technical support are included, starting with the first interaction. Additional maintenance and support options are available.